A large study of infertile women in Denmark concluded that using fertility drugs does not increase a woman’s risk of developing ovarian cancer.

The study was the work of researchers from the Danish Cancer Society at the Institute of Cancer Epidemiology in Copenhagen, and The Juliane Marie Center at Copenhagen University Hospital, and was published online on 5 February in bmj.com.

Over the past thirty years or so scientists have argued about whether using fertility drugs increases the risk of ovarian cancer. Studies have yielded conflicting results and many women and their doctors remain concerned, especially in those cases where women have several cycles of fertility treatment, or who never become pregnant.

For the study, Dr Allan Jensen assistant professor of cancer epidemiology at the Danish Cancer Society, and colleagues, examined the records of 54,362 women with infertility problems who attended Danish fertility clinics between 1963 and 1998. This is the largest group of infertile women to be studied in this way, and of these, 156 women had ovarian cancer.

Jensen and colleagues looked for links between four types of fertility drugs (gonadotrophins, clomiphene citrate, human chorionic gonadotrophin, and gonadotrophin releasing hormone) and ovarian cancer over an average period of 16 years. The median age at first evaluation of infertility was 30 years (ranging from 16 to 55 years) and at the end of follow up it was 47 (ranging from 18 to 81).

They adjusted the figures to rule out effects from other risk factors and found no overall increased risk for ovarian cancer linked to use of any of the fertility drugs. There was also no increased risk among women who had 10 or more cycles of treatment or among women who did not get pregnant.

However, they did find a statistically significant increase in risk of the most common serious type of ovarian cancer in those women who took the drug clomiphene, but decided this was a “chance association”.

The researchers concluded that:

“No convincing association was found between use of fertility drugs and risk of ovarian cancer.”

In a prepared statement they said the results were “generally reassuring”, but they did point out that many of the participants had not yet reached the peak age for ovarian cancer, which is in the early 60s (most of the women in this study were in their late 40s at the end of follow up), so they will be continuing to monitor them.

They also said that any potential side effects of fertility drugs should be balanced against the physical and psychological benefits of a pregnancy made possible only through their use, particularly in this day and age when more and more women are infertile and choose to have their first child later in life.

In an accompanying editorial, Dr Penelope Webb of the Queensland Institute of Medical Research, wrote that the study results were reassuring and give further evidence that fertility drugs do not significantly increase ovarian cancer risk, but they do not rule out the possibility of small increases in risk.

According to the US Centers for Disease Control and Prevention (CDC), over 20,000 women were diagnosed with ovarian cancer in the US in 2004, making it the second most common gynecologic cancer (the first being endometrial cancer, carcinoma of the lining of the uterus). Ovarian cancer causes more deaths than any other gynecologic cancer, but it accounts for only about 3 percent of all cancers in women.

Ovarian cancer is not easy to detect and many women don’t find out they have it until it has reached an adavanced stage. Symptoms include pain in the pelvis or abdomen, back pain, feeling tired all the time, bloating feeling in the stomach, more frequent and/or difficult urination, upset stomach or heartburn, vaginal discharge. Pain during sexual intercourse can also be a symptom.

“Use of fertility drugs and risk of ovarian cancer: Danish population based cohort study.”
Allan Jensen, Heidi Sharif, Kirsten Frederiksen, Susanne Krüger Kjær.
BMJ 2009;338:b249, (Published 5 February 2009)
doi: 10.1136/bmj.b249

Click here for Abstract.

Sources: BMJ-British Medical Journal .

Written by: Catharine Paddock, PhD